Telecommunication systems include customer premise equipment (CPE), local loops connecting each customer premise to a central office (CO) or other node, the nodes providing switching and signaling for the system, and internode trunks connecting the various nodes. The customer premise equipment (CPE) includes telephones, modems for communicating data over phone lines, computer and other devices that can directly communicate video, audio, and other data over a data link. The network nodes include traditional circuit-switch nodes which have transmission paths dedicated to specific users for the duration of a call and employ continuous, fixed-bandwidth transmission as well as packet-switch nodes that allow dynamic bandwidths, dependent on the application. The transmission media between the nodes may be wireline, wireless, or a combination of these or other transmission medias.
Telecommunication nodes typically use parallel buses across a backplane between a node controller and service, line, or other units of the node. On a parallel bus, integrity can be effected by the insertion and removal of units on the bus. In addition, a single unit failure can cause the bus to also fail. Another problem with parallel buses is that a large amount of input/output (I/O) pins to the backplane are required for a wide bus. Although multiplexing of the bus can reduce the pin count, a substantial number of pins are nevertheless required.